[flashrom-gerrit] [M] Change in flashrom[master]: flashrom: Check for flash access restricitons erase path

[Nikolai Artemiev (Code Review)]

Attention is currently required from: Edward O'Callaghan.

Hello Edward O'Callaghan,

I'd like you to do a code review.
Please visit

https://review.coreboot.org/c/flashrom/+/70517

to review the following change.

Change subject: flashrom: Check for flash access restricitons erase path
......................................................................

flashrom: Check for flash access restricitons erase path

Skip unwritable regions if FLASHROM_FLAG_SKIP_UNWRITABLE_REGIONS is
true. If the flag is false, erase operations that include an unwritable
region will not erase anything and return an error.

BUG=b:260440773
BRANCH=none
TEST=flashrom -E on dedede (JSL)

Change-Id: If027a96a024782c7707c6d38680709a1a117f3ef
CoAuthored-by: Edward O'Callaghan 
Signed-off-by: Edward O'Callaghan 
Signed-off-by: Nikolai Artemiev 
---
M flashrom.c
1 file changed, 53 insertions(+), 5 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/17/70517/1

diff --git a/flashrom.c b/flashrom.c
index 7a77845..23af5da 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -1410,13 +1410,41 @@
    all_skipped = false;

msg_cdbg("E");
-	if (erasefn(flashctx, info->erase_start, erase_len))
-		goto _free_ret;
-	if (check_erased_range(flashctx, info->erase_start, erase_len)) {
-		msg_cerr("ERASE FAILED!\n");
-		goto _free_ret;
+
+	unsigned int len;
+	for (unsigned int addr = info->erase_start; addr < info->erase_start + erase_len; addr += len) {
+		struct flash_region region;
+		get_flash_region(flashctx, addr, &region);
+
+		len = min(info->erase_start + erase_len, region.end) - addr;
+
+		if (region.write_prot) {
+			if (flashctx->flags.skip_unwritable_regions) {
+				msg_gdbg("%s: cannot erase inside %s region (%#08x..%#08x), skipping range (%#08x..%#08x).\n",
+					 __func__, region.name, region.start, region.end - 1, addr, addr + len - 1);
+				free(region.name);
+				continue;
+			}
+
+			msg_gerr("%s: cannot erase inside %s region (%#08x..%#08x).\n",
+				 __func__, region.name, region.start, region.end - 1);
+			free(region.name);
+			return -1;
+		}
+
+		msg_gdbg("%s: %s region (%#08x..%#08x) is writable, erasing range (%#08x..%#08x).\n",
+			 __func__, region.name, region.start, region.end - 1, addr, addr + len - 1);
+		free(region.name);
+
+		if (erasefn(flashctx, addr, len))
+			goto _free_ret;
+		if (check_erased_range(flashctx, addr, len)) {
+			msg_cerr("ERASE FAILED!\n");
+			goto _free_ret;
+		}
    }

+
    if (region_unaligned) {
    	unsigned int starthere = 0, lenhere = 0, writecount = 0;
    	/* get_next_write() sets starthere to a new value after the call. */